/*
FUNCTION
	<<memmove>>---move possibly overlapping memory

INDEX
	memmove

ANSI_SYNOPSIS
	#include <string.h>
	void *memmove(void *<[dst]>, const void *<[src]>, size_t <[length]>);

TRAD_SYNOPSIS
	#include <string.h>
	void *memmove(<[dst]>, <[src]>, <[length]>)
	void *<[dst]>;
	void *<[src]>;
	size_t <[length]>;

DESCRIPTION
	This function moves <[length]> characters from the block of
	memory starting at <<*<[src]>>> to the memory starting at
	<<*<[dst]>>>. <<memmove>> reproduces the characters correctly
	at <<*<[dst]>>> even if the two areas overlap.


RETURNS
	The function returns <[dst]> as passed.

PORTABILITY
<<memmove>> is ANSI C.

<<memmove>> requires no supporting OS subroutines.

QUICKREF
	memmove ansi pure
*/

#include <section_config.h>
#include <basic_types.h>

#include <string.h>
#include <_ansi.h>
#include <stddef.h>

//#include "local.h"

#ifdef _HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
# define __inhibit_loop_to_libcall __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
#else
# define __inhibit_loop_to_libcall
#endif

/* Nonzero if either X or Y is not aligned on a "long" boundary.  */
#define UNALIGNED(X, Y) \
  (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))

/* How many bytes are copied each iteration of the 4X unrolled loop.  */
#define BIGBLOCKSIZE    (sizeof (long) << 2)

/* How many bytes are copied each iteration of the word copy loop.  */
#define LITTLEBLOCKSIZE (sizeof (long))

/* Threshhold for punting to the byte copier.  */
#define TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)

/*SUPPRESS 20*/
LIBC_ROM_TEXT_SECTION
_LONG_CALL_
void *__inhibit_loop_to_libcall _memmove(void *dst_void, const void *src_void, size_t length)
{
#if defined(PREFER_SIZE_OVER_SPEED)
	char *dst = dst_void;
	const char *src = src_void;

	if (src < dst && dst < src + length) {
		/* Have to copy backwards */
		src += length;
		dst += length;
		while (length--) {
			*--dst = *--src;
		}
	} else {
		while (length--) {
			*dst++ = *src++;
		}
	}

	return dst_void;
#else
	char *dst = dst_void;
	const char *src = src_void;
	long *aligned_dst;
	const long *aligned_src;

	if (src < dst && dst < src + length) {
		/* Destructive overlap...have to copy backwards */
		src += length;
		dst += length;
		while (length--) {
			*--dst = *--src;
		}
	} else {
		/* Use optimizing algorithm for a non-destructive copy to closely
		   match memcpy. If the size is small or either SRC or DST is unaligned,
		   then punt into the byte copy loop.  This should be rare.  */
		if (!TOO_SMALL(length) && !UNALIGNED(src, dst)) {
			aligned_dst = (long *)dst;
			aligned_src = (long *)src;

			/* Copy 4X long words at a time if possible.  */
			while (length >= BIGBLOCKSIZE) {
				*aligned_dst++ = *aligned_src++;
				*aligned_dst++ = *aligned_src++;
				*aligned_dst++ = *aligned_src++;
				*aligned_dst++ = *aligned_src++;
				length -= BIGBLOCKSIZE;
			}

			/* Copy one long word at a time if possible.  */
			while (length >= LITTLEBLOCKSIZE) {
				*aligned_dst++ = *aligned_src++;
				length -= LITTLEBLOCKSIZE;
			}

			/* Pick up any residual with a byte copier.  */
			dst = (char *)aligned_dst;
			src = (char *)aligned_src;
		}

		while (length--) {
			*dst++ = *src++;
		}
	}

	return dst_void;
#endif /* not PREFER_SIZE_OVER_SPEED */
}
